Subtract 90/20 from 21/30
1st number: 21/30, 2nd number: 4 10/20
21/30 - 90/20 is -19/5.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 20 is 60
Next, find the equivalent fraction of both fractional numbers with denominator 60 - For the 1st fraction, since 30 × 2 = 60,
21/30 = 21 × 2/30 × 2 = 42/60 - Likewise, for the 2nd fraction, since 20 × 3 = 60,
90/20 = 90 × 3/20 × 3 = 270/60 - Subtract the two like fractions:
42/60 - 270/60 = 42 - 270/60 = -228/60 - After reducing the fraction, the answer is -19/5
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/30-90/20 21/60-90/20 21/30-90/40 63/30-90/20 21/90-90/20 21/30-90/60